The present invention relates generally to a piston pump elevator having fluid level measurement capability. More particularly, the present invention relates to a piston pump elevator having fluid level measurement capability which is capable of outputting an electrical signal proportional to the approximate amount of fluid remaining in a container from which fluid is being withdrawn.
Piston pump elevators are commonly used to withdraw fluid from a container, such as, for example, a fifty five (55) gallon drum. In many situations, it is useful to know approximately how much fluid remains in a container from which fluid is being withdrawn for the purposes of, for example, tracking material inventory usage and forecasting usage. Unfortunately, many convention piston pump elevators utilize a follower plate positioned over the fluid which precludes the use of many conventional fluid level measuring techniques and devices. For example, fluid measurement techniques and devices utilizing ultrasonic, static pressure, capacitive and float level are generally not practical for conventional piston pump elevators since they require access to the top level of the fluid remaining in the container from which fluid is being withdrawn.
Accordingly, some conventional piston elevators utilize a mechanical limit switch to indicate when a container is completely or substantially empty. However, conventional piston elevators utilizing a mechanical limit switch do not provide information as to how much fluid remains in a container from which fluid is being withdrawn until the container is completely or substantially empty.
In addition, one can visually observe and/or physically measure the position of a follower plate in a conventional piston pump elevator to estimate the approximate amount of fluid remaining in the container from which fluid is being withdrawn. However, visually observing and/or physically measuring the position of a follower plate in a conventional piston pump elevator requires one to be physically present to visually observe and/or physically measure the position of the follower plate to estimate the approximate amount of fluid remaining in the container from which fluid is being withdrawn.
Accordingly, an object of the present invention is the provision of a piston pump elevator having fluid level measurement capability which allows the approximate amount of fluid remaining in a container from which fluid is being withdrawn to be measured without one being physically present to visually observe and/or physically measure the position of the follower plate.
Another object of the present invention is to provide a piston pump elevator having fluid level measurement capability which is capable of outputting an electrical signal proportional to the approximate amount of fluid remaining in a container from which fluid is being withdrawn.
Yet another object of the present invention is to provide a piston pump elevator having fluid level measurement capability which is capable of outputting an electrical signal proportional to the approximate amount of fluid remaining in a container from which fluid is being withdrawn which can be used by other electronic devices, such as an electronic inventory control system, to remotely indicate the approximate amount of fluid remaining in a container from which fluid is being withdrawn.
These and other objects of the present invention are attained by the provision of a piston pump elevator having fluid level measurement capability which is capable of outputting an electrical signal proportional to the approximate amount of fluid remaining in a container from which fluid is being withdrawn. In particular, a first preferred embodiment of the piston pump elevator includes a hook which is mounted on a crossbar and a cable extension transducer which is mounted to the piston pump elevator and its sensing element or cable connects to the hook. The sensing element is capable of measuring the position of said follower plate in relation to the container and providing an output signal. The transducer which is capable of receiving said output signal from said sensing element and providing an output voltage proportional to the approximate amount of the fluid remaining in the container from which the fluid is being withdrawn. Thus, as the follower plate rises, cable is drawn out from the cable extension transducer and its output voltage changes at a rate of, for example, one (1) volt per five (5) gallons of fluid remaining in the container from which fluid is being withdrawn. A second preferred embodiment of a piston pump elevator having fluid level measurement capability utilizes a polished tube, rather than a solid rod, for the cylinder rod which is attached to a crossbar by a sealing screw. The piston contains a through hole and a pocket for a sensing element, such as a magnet for a magnetostrictive transducer or a sliding contact for a linear resistance transducer. The sensing element transducer is mounted firmly at the bottom of the cylinder and electrical signals from the sensing device transducer are available through a connector. As in the first embodiment, the sensing element is capable of measuring the position of said follower plate in relation to the container and providing an output signal; and the transducer is capable of receiving said output signal from said sensing element and providing an output voltage proportional to the approximate amount of the fluid remaining in the container from which the fluid is being withdrawn. As the piston pump elevator raises the follower plate by pressurizing the bottom of the pistons on either side, the sensing element transducer raises as well. The sensing element transducer outputs a voltage signal proportional to the distance of the sensing element from its base. Thus, again, the output voltage changes at a rate proportional to the approximate amount of fluid remaining in the container from which fluid is being withdrawn.